Drug Delivery and Translational Research

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Temperature-responsive PNDJ hydrogels provide high and sustained antimicrobial concentrations in surgical sites Abstract Local antimicrobial delivery is a promising strategy for improving treatment of deep surgical site infections (SSIs) by eradicating bacteria that remain in the wound or around its margins after surgical debridement. Eradication of biofilm bacteria can require sustained exposure to high antimicrobial concentrations (we estimate 100–1000 μg/mL sustained for 24 h) which are far in excess of what can be provided by systemic administration. We have previously reported the development of temperature-responsive hydrogels based on poly(N-isopropylacrylamide-co-dimethylbutyrolactone acrylate-co-Jeffamine M-1000 acrylamide) (PNDJ) that provide sustained antimicrobial release in vitro and are effective in treating a rabbit model of osteomyelitis when instilled after surgical debridement. In this work, we sought to measure in vivo antimicrobial release from PNDJ hydrogels and the antimicrobial concentrations provided in adjacent tissues. PNDJ hydrogels containing tobramycin and vancomycin were administered in four dosing sites in rabbits (intramedullary in the femoral canal, soft tissue defect in the quadriceps, intramuscular injection in the hamstrings, and intra-articular injection in the knee). Gel and tissue were collected up to 72 h after dosing and drug levels were analyzed. In vivo antimicrobial release (43–95% after 72 h) was markedly faster than in vitro release. Drug levels varied significantly depending on the dosing site but not between polymer formulations tested. Notably, total antimicrobial concentrations in adjacent tissue in all dosing sites were sustained at estimated biofilm-eradicating levels for at least 24 h (461–3161 μg/mL at 24 h). These results suggest that antimicrobial-loaded PNDJ hydrogels are promising for improving the treatment of biofilm-based SSIs.

Combined chitosan and Dan-shen injection for long-term tubal patency in fallopian tube recanalization for infertility Abstract To prospectively study the efficacy of different anti-adhesion agents for the prevention of tubal obstruction after recanalization, this trial was approved by our hospital ethics committee. Four hundred patients with fallopian tube obstruction were randomly assigned to four groups. The control group underwent recanalization alone, whereas the other groups were injected with chitosan, Dan-shen, or combined chitosan and Dan-shen after recanalization. The tubal patency rate in all four groups was recorded after 12 day, 3 months, and 12 months. The pregnancy rates were noted after 12 months. The recanalization rates after 1 day in the control, chitosan, Dan-shen, and combined chitosan and Dan-shen groups were 94.1, 97.1, 96.5, and 98.2%, respectively (p = 0.18, p > 0.05). The rates of tubal patency after 3 months were significantly higher in the combined chitosan and Dan-shen (96.5%), chitosan (88%), and Dan-shen (85.2%) groups compared with the control group (73.9%) (p = 0.0001, p < 0.05). The recanalization rate and intrauterine pregnancy rate after 12 months was significantly higher in the combined chitosan and Dan-shen group (93.8 and 63.9%, respectively) compared with the other groups (control 39 and 30.6%, chitosan 78.4 and 46.9%, and Dan-shen 77.3 and 43.3%) (p = 0.0029 and p = 0.0001, p < 0.05). Chitosan, Dan-shen, or a combination of the two compounds could be effective for preventing tubal obstruction after interventional recanalization, possibly increasing the rate of pregnancy in affected women. The combined chitosan and Dan-shen injection has unique advantages in the interventional recanalization of obstructed fallopian tubes.

Tetrahydrocurcumin-loaded vaginal nanomicrobicide for prophylaxis of HIV/AIDS: in silico study, formulation development, and in vitro evaluation Abstract A vaginal microbicide is a front-line women-dependent approach and an alternative to a condom for prevention of unprotected sexual intercourse-associated HIV. The microbicide research is still in its infancy with several products in the clinical studies being reported to have good efficacy, safe, but with poor adherence. One such molecule reported with an excellent efficacy when tested preclinically is curcumin, a natural polyphenol derived from Curcuma longa. Despite its potential HIV-1 inhibitory activity, it has intense yellow color staining properties, which would result in poor consumer compliance and adherence for vaginal application. To address this issue, tetrahydrocurcumin (THC), a colorless derivative of curcumin, was subjected to in silico screening (molecular docking and dynamics simulation studies) using homology model of gp120-CD4 binding. It was found that THC exhibited equivalent gp120-CD4 binding inhibitory activity as compared with curcumin due to its stable hydrophobic interactions with residues Asp368 and Trp427 deeper in the Phe43 cavity of CD4 receptor. Hence, it can be effectively used as a potential microbicide candidate. THC, a BCS Class II molecule exhibits poor solubility, spreadability, and intracellular uptake when used in the conventional form. Thus, it was decided to develop a lipid-based nanomicrobicide gel for delivery of THC. The developed THC-loaded o/w microemulsion gel was characterized for physicochemical properties (globule size, drug content, drug release, and permeation) and further used for in vitro cell line studies (cell viability, cellular uptake, and anti-HIV activity). The developed formulation was found to be stable with coitus-independent release profile and exhibited a rapid time-independent intracellular uptake. In addition, it exhibited a fourfold increase in efficacy as compared with conventional THC. Thus, the novel THC-loaded o/w microemulsion gel exhibited the potential for prevention of HIV-1 infection associated with unprotected sexual intercourse.

Evaluation of microneedles-assisted in situ depot forming poloxamer gels for sustained transdermal drug delivery Abstract In this study, for the first time, we have reported a sustained transdermal drug delivery from thermoresponsive poloxamer depots formed within the skin micropores following microneedle (MN) application. Firstly, we have investigated the sol–gel phase transition characteristics of poloxamers (PF®127, P108, and P87) at physiological conditions. Rheological measurements were evaluated to confirm the critical gelation temperature (CGT) of the poloxamer formulations with or without fluorescein sodium (FS), as a model drug, at various concentrations. Optimized poloxamer formulations were subjected to in vitro release studies using a vial method. Secondly, polymeric MNs were fabricated using laser-engineered silicone micromolds from various biocompatible polymeric blends of Gantrez S-97, PEG 10000, PEG200, PVP K32, and PVP K90. The MN arrays were characterized for mechanical strength, insertion force determination, in situ dissolution kinetics, moisture content, and penetration depth. The optimized MN arrays with good mechanical strength and non-soluble nature were used to create micropores in the neonatal porcine skin. Microporation in neonatal porcine skin was confirmed by dye-binding study, skin integrity assessment, and histology study. Finally, the in vitro delivery of FS from optimized poloxamer formulations was conducted across non-porated vs microporated skin samples using vertical Franz diffusion cells. Results concluded that permeation of FS was sustained for 96 h across the MN-treated skin samples containing in situ forming depot poloxamer formulations compared to non-microporated skin which sustained the FS delivery for 72 h. Confocal microscopic images confirmed the distribution of higher florescence intensity of FS in skin tissues after permeation study in case of MN-treated skin samples vs intact skin samples.

Skin test of tuberculin purified protein derivatives with a dissolving microneedle-array patch Abstract Background The tuberculin skin test (TST) is a long-established screening method for tuberculosis. However, the Mantoux technique is often difficult to reliably perform, which affects testing results and safety, which causes local skin pain and pruritus. Methods In this study, dissolving microneedle-array patches (MNP) were used to deliver purified protein derivative (PPD) tuberculin into the skin. The skin reaction was compared between MNP delivery and conventional injection. Results The MNP penetrated the skin easily with a thumb press, and the microneedle dissolved into the skin completely after 1 h. The storage life of MNP loaded with PPD (MNP-PPD) was 7 weeks at atmospheric pressure and room temperature. Only 1/50 dosage of PPD (approximately 0.04 IU) was needed in MNP compared with conventional injection (2 IU) in terms of skin reactivity to TST. When TST was tested in volunteers, the redness and induration of the skin were 19.7 ± 5.6 mm in TB patients, 12.6 ± 4.4 mm in LTBI (latent TB infection) patients, and 5.8 ± 2.7 mm in BCG vaccination healthy volunteers and lasted approximately 26 ± 5.4 days. When applied with MNP-PPD, the redness and induration on the skin decreased significantly to 3.1 ± 0.7 mm in TB patients and 2.0 ± 0.5 mm in LTBI, and the duration time was only 8.5 ± 1.5 days. Moreover, despite the relatively mild skin reactivity in BCG vaccination healthy volunteers with conventional injection, there was no skin reactivity in BCG vaccination healthy volunteers with MNP-PPD. Conclusion In addition to being minimally invasive, needle-free, and painless, no adverse effects were attributed to the new diagnostic method, which may be of value for the safe and effective clinical administration of TB screening. When applied with MNP-PPD, an area of redness and induration greater than 2.5 mm can identify a TB-positive patient.

Formulation of topical ibuprofen solid lipid nanoparticle (SLN) gel using hot melt extrusion technique (HME) and determining its anti-inflammatory strength Abstract Solid lipid nanoparticles (SLN) have been formulated using various batch processes, e.g., solvent diffusion evaporation, emulsification solvent evaporation followed by size reduction using high-pressure homogenization (HPH) or ultrasonication. However, for the manufacturing of formulations, continuous processes are always preferred over batch processes since they are more efficient and offer better quality of the end product. Hence, we developed topical SLN of ibuprofen (IBU) using hot melt extrusion (HME), prepared a gel formulation, and performed its in vitro and in vivo evaluation. Effect of different variables of HME equipment and materials used in SLN was optimized using design of experiment (DoE) approach. Stable 0.48% IBU SLN with particle size 60.2 ± 4.81 nm and entrapment efficiency 90.41 ± 3.46% were developed which further gelled using 1% carbopol 981A. Drug release study, skin deposition study, and in vivo anti-inflammatory activity studies showed 84.37 ± 4.65% drug release, 12.05 ± 0.81% drug deposition, and 40.17 ± 2.41% edema inhibition respectively in case of IBU SLN gel (IBU-SLN-G) which was significantly higher (p < 0.05) than control IBU gel (C-IBU-G) with 50.11 ± 0.57% drug release, 4.11 ± 1.10% deposition, and 20.08 ± 3.23% edema inhibition respectively. In conclusion, HME offers a single step process for manufacturing for SLN which avoids high stress particle size reduction techniques used for SLN preparation.

Mechanics of controlled release of insulin entrapped in polyacrylic acid gels via variable electrical stimuli Abstract Controlled release insulin delivery systems possess multiple advantages over conventional ones, including maintaining desired blood glucose levels for prolonged periods and minimizing complications due to insulin overdose. Compared to other controlled-release mechanisms, electro-responsive polymers present the advantages of high controllability and ability to be coupled with microelectronics. This paper reports the possibility of using electro-responsive polyacrylic acid (PAA) and polymethacrylic acid (PMA) hydrogels for controlled delivery of insulin using intermittent electrical signals via matrix deformation. PAA hydrogels showed very good electrical responsivity under both constant and step current inputs, releasing up to 80% of protein at 10 V stimulus, compared to 20% release in the absence of stimulus. Analysis of spatial variation under electrical stimuli suggested that release of protein is a combined effect of deformation of the hydrogel and electrophoresis of protein molecules. Binding interaction analysis revealed that insulin entrapment is largely due to hydrogen bonding between the polymer matrix and insulin, and flooding the matrix with electrical charge likely disrupts the attractive forces that kept protein in place helping the release of the proteins. Understanding the molecular interactions affecting insulin retention and release mechanisms of PAA hydrogels is useful for developing and optimizing hydrogel-based controlled drug release systems.

Nano-engineered lipid-polymer hybrid nanoparticles of fusidic acid: an investigative study on dermatokinetics profile and MRSA-infected burn wound model Abstract Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) have been a major cause of morbidity in thermally injured patients. The skin barrier gets disrupted and loss of immunity further makes burn sites an easy target for bacterial colonization. In the current study, combined potential of lipid-polymer hybrid nanoparticles (LPHNs) with fusidic acid was explored as a promising strategy toward combating resistant bacteria in burn wound infection sites. The developed systems exhibited particle size (310.56 ± 5.22 nm), zeta potential (24.3 ± 4.18 mV) and entrapment efficiency (78.56 ± 3.56%) with a spherical shape. The hybrid nanoparticles were further gelled into carbopol and demonstrated better permeation (76.53 ± 1.55%) and retention characteristics (56.41 ± 4.67%) as compared to the conventional formulation. The topical delivery of FA into the skin layers by FA-LPHN gel was found to be significantly higher (p < 0.05) compared to FA-CC. The in vivo potential was further assessed in murine burn wound model inflicted with MRSA 33591 bacterium with the determination of parameters like bacterial burden, wound contraction, morphological and histopathological examination of wounds. The bacterial count decreased drastically in FA-LPHN gel group (5.22 log CFU/mL) on day 3 with significant difference in comparison to FA-CC. The wound size reduction in FA-LPHN gel (68.70 ± 3.65%) was higher as compared to FA-CC (73.30 ± 4.23%) and control groups (83.30 ± 4.40%) on day 5. The current study presents a safe and effective formulation strategy for the treatment of MRSA-infected burn wounds by providing moist environment and prevention from bacterial infection.

A three-pronged formulation approach to improve oral bioavailability and therapeutic efficacy of two lipophilic drugs with gastric lability Abstract The aim of present study was to co-administer curcumin (CRM) liquisolid pellets and coated duloxetine hydrochloride (DXH) pellets in rats to treat neuropathic pain (NP) associated with chronic constriction injury (CCI). To formulate liquisolid pellets of CRM, it was first dissolved in Tween-80 and then adsorbed on the porous surface of MCC PH102 and Syloid XDP that were used as carrier and coating materials, respectively. Central composite design was used to optimize the liquisolid formulation. The results of powder X-ray diffraction studies, differential scanning calorimetry, and scanning electron microscopy showed complete solubility of drug in Tween-80 followed by its complete adsorption on the porous surface of Syloid XDP and MCC PH102. Both DXH and liquisolid CRM powders were converted into pellets using extrusion-spheronization. DXH pellets were further coated with Eudragit S100 to bypass the gastric pH. About 32.31-fold increase in dissolution rate of CRM present in liquisolid formulation was observed as compared to its unprocessed form. Similarly, the dissolution profile in 0.1 N HCl for Eudragit S100-coated DXH showed complete protection of drug for 2 h and complete release after its introduction in buffer medium (0.2 M phosphate buffer pH 6.8). he pharmacokinetic studies carried out on rats revealed 7.3-fold increase in bioavailability of CRM present in liquisolid pellets and 4.1-fold increase in bioavailability of DXH present in coated pellets was observed as compared to their unprocessed pellets. This increase in bioavailability of drugs caused significant amelioration of CCI-induced pain in rats as compared to their unprocessed forms. The histological sections showed better improvement in regeneration of nerve fibers in rats.